Dear friends, in the following seminar we will talk about suturing and suture techniques in periodontal and implant surgery. For sure this is a topic that is interesting and important for everybody who is practicing this kind of surgery. Suturing does not only mean to approximate two flat edges with each other, suturing also means to stabilize a wound or in other words, to maintain the stability of the blood clot underneath the wound or in the wound which happens in all kind of situations of the surgery. So we have to talk about suture techniques and the suture materials. There is something unique in periodontal and peri-implant surgery. It is the fact that we try to restore or replace soft tissues on vascular non-shedding surfaces. On such kind of surfaces, the blood clot adherence is not the same as on a connective tissue wound bed. On the right side, you see the suturing after a recession coverage. Several sutures that firmly fix the flap on the wound bed. If there is mobility in the wound area, the blood clot will disrupt and this will for sure influence the healing. The blood clot underneath the flap is the most elastic polymer the human body can perform but not all of the blood clots are the same. Did you know that different patients have different clots with different behaviours? So, for example the blood clot of obese patients or of diabetic patients produce fibrin fibers that are thicker than in other circumstances, so a fibrin clot that is consisting of thin fibers with many branch points is more elastic than a fibrin clot that consisting of thick fibers. For comparison, I show you this slide on the right. You see the elasticity in the graph of the difference between a collagen fiber and a fibrin fiber. You can see that the fibrin fiber is elastic to a much higher amount of force. And then when you extend the fiber beyond the certain extent, the molecule will be irreversibly damaged. That means that we as clinicians can influence the force that we bring to the clot or to the fibrin fiber. That means that when we suture a flap with some tension, we will damage either irreversibly the clot and influence the healing. So just by choosing thinner suture diameters, we can influence the force that we bring to the clot. We will talk about this later on. There are several studies that investigated the clinical behavior of the clot. For example, a clot under tension resorbs more slower than a clot that is not under tension. On one side, the clot has to be an open structure to allow access to the fibroblast, on the other hand, it must be a firm structure to resist towards the forces that are applied. So again, as clinicians, we influence the resorption time of the clot by the forces brought to the wound. Another important fact is the ingrowth of capillaries. It has been shown that a clot under tension is slowly re-vascularized than the clot without tension. Cells from the endothelium, from the surrounding capillaries will ingrow but if the clot is under tension, lumen formation does not take place. In the next section, we will talk about suture material, that means the needle and the suture strand. So these two components are important for the suture. Regarding the needle, usually, in periodontal surgery, we are working with 3/8 curvature needles. These allow a right angled entry and a right angled exit in the tissues. When we come too close to teeth and we suture releasing incisions, we have to choose a needle form that has more curvature, that means a half circle curvature or an asymptotically curved needle which changes the curvature in each segment of the bow. An important aspect of the needle is the tip. Usually, we are dealing with very coarse tissues, that's why the needle tips have to be very sharp. It depends on the tissues. If for example we have to suture the Schneiderian membrane in a sinus augmentation, the needle tip have to be rounded, otherwise the tearing will open again or more if we have a very sharp needle. When we are suturing, we have to grasp the needle in the middle part, never at the tip in order not to damage the tip or not in the lock where the suture strand is attached to the needle. In some needles, the strand is attached by clamping the needle. And in others, there is a laser-drilled hole where the suture strand is adhesively fixed. On these slides you'll see in high magnification the damage to the tissues which depends not only on the size of the needle tip but also mainly on the lock of the needle. A laser-drilled hole damages less than a clamping attachment of the needle and the strand. But it's not only the configuration and the length of the needle, it's also the material, namely the steel which will influence the behaviour of the needle. There are steels that allow more flexibility of the needle. That means when you touch the needle, it will less bend compared to other needles. When we talk about suture strand, there are three different main modalities. We have the monofilament sutures, the polyfilament ones, and the pseudo-monofilament ones. Pseudo-monofilament ones means polyfilament ones that have a coating and a smoother outer surface. Generally, the polyfilament ones show more sewing effects when they are pulled through the tissues. That's why we prefer the monofilament ones. Here you see in high magnification the differences and you can easily imagine that in aqueous solution and bacterial-loaded environments that the adherence of bacteria will be more pronounced in polyfilament ones than in monofilament ones. Gore-Tex or polytetrafluoroethylene is a special material with very convenient handling properties. But as the material is stretched, the surface is bigger and the adherence of the bacteria will be more pronounced than on smooth monofilament ones.
